The present invention relates to a thermal recording stylus for recording on a thermal recording paper.
Recently a thermal recording system has become extensively used as a substitute for a pen-and-ink recording system in such a field as an analog recorder for a measuring instrument. A quick thermal response character, a fine resolution in drawing a line, and an excellent abrasion-resistant property are required for the recording head of a thermal recording stylus. For the purpose of improving the abrasion-resistant property, an abrasion-resistant layer made of glass mixed with powder of such crystallized Al.sub.2 O.sub.3 as sapphire or ruby, has hitherto been used for the coating of the recording head. But the abrasion-resistant property of this type of the recording head has not been satisfactory, and this type of the recording head can be used to record a maximum of about 500 km line length when used under a stylus pressure of 20 g on the recording paper. And the heat conductivity of this abrasion-resistant layer is comparatively poor, and is in the order of 0.0016-0.0034 cal/cm.sup.2. sec..degree.C. when the layer is made of glass mixed with powder of the crystallized Al.sub.2 O.sub.3. This poor heat conductivity has been the cause of the slow thermal response character of the heretofore known thermal recording stylus at the switching-on and switching-off transients of the heating power to the thermal recording stylus.